All errors related to OABGen should be written to the event log. After that you can use cmdlets below, it will find/count all OAB errors ($OABerrors) and take out names of skipped users ($OABerrorsUser).

Variable $OABerrorsUser could be used for another loop based on your needs of repairs.

Event ID: 9325 basically occurs because the recipient’s primary SMTP address (PrimarySmtpAddress) was changed without updating the Mail attribute (WindowsEmailAddress). If the Mail attribute does not match the primary SMTP address, the recipient will be dropped when the offline address book is generated. Description how to solve this issue is shown here: Using Powershell to Correct 9325 Events in Exchange 2007

The event could occur also for mail-disabled users if ShowInAddressBook attribute is not clear <not set>. All mail-enabled objects have this attribute always filled in (including users, contacts, groups, public-folders). The attribute can be erased via ADSI Edit or Active Directory Module for Windows PowerShell.